Particle Field

Particles are useful for creating water sprays and fountains, sparks and explosion effects. In each of these situations, particles are unaware of the other particles' motions or positions in space. This is why particles seem to scatter.

Observing the dynamics of fluids like water or an oily substance, we can see that fluids have a cohesive property. Each particle of a fluid has a relationship with the others. Particle Field surrounds EACH particle with a force field (similar to the force field in the Force Field controller). When two particles come close to one another, they can attract or repel each other. This relationship can allow a group of particles to maintain a certain distance from one another. The effect is very useful for filling a container with water or creating gel and ooze. Using Particle Field with other effects like Force Fields and Collisions, you can even create splashing effects.

• Clone: Makes a copy of this controller. All parameter values and envelopes are copied.
• Delete: Delete a controller from the Controller list.
• Activate/Deactivate: This activates or deactivates the controller from having any effect on the simulation.

• Cutoff Radius: This defines the radius of the sphere of influence (you can think of this as each particle having a sphere around them). When these spheres of influence intersect or move through one another, the particles begin affecting each other.
• Happy Radius: Similar to the Cutoff Radius, this defines a sphere of effect around each particle. When these spheres intersect or move through one another, particles begin to attract or repel each other.
  
  Particles will repel each other if their spheres of influence defined by the Happy Radius are intersecting (see illustration below). The amount of repulsion depends on how far the two spheres intersect. As the distance between the center point of these spheres (namely each particle) get closer, the harder they will repel each other. This is useful when you don't want the particles to crash into each other. For example, if you are using the Flocking and Swarming controller, you wouldn't want your bees flying into and through each other.
  
  Particles will attract each other if their spheres of influence defined by the Happy Radius are not touching each other (see illustration below), but are still within the sphere of influence defined by the Cutoff Radius. The amount of attraction will depend on how much these spheres are intersecting. This feature can create ooze, gel, mercury, water, and other similar effects.
• Repel Strength: How strongly the particles repel each other.
• Repel Falloff Exponent: Determines how the repel strength falls off with increasing distance. See graph for details.
• Attract Strength: How strongly the particles attract each other.
• Attract Falloff Exponent: Determines how the strength of attraction falls off based on distance.
• Bounding Shape: A bounding shape for the entire effect. Any particle outside the bounding shape will be completely unaffected by the Particle Field Controller.

Outer spheres are intersecting.	Inner spheres are intersecting.